1. Field of the Invention
The present invention relates to a secondary battery and capacitor, and more particularly to a secondary battery and capacitor in which an indole polymeric compound is used as an electrode active material and a proton is employed as a charge carrier thereof.
2. Description of the Related Art
As an invention that employs indole, JP 5-148320A discloses a method of chemical-oxidative polymerization of indole monomers to obtain polyindole, and a conductive device that contains polymers polymerized through the method. The indole is limited only to the polyindole and the use of the conductive device is only for conductive films and electrochromic devices.
A paper on xe2x80x9cElectrochemical synthesis of polyindole and its evaluation for rechargeable battery applicationsxe2x80x9d describes a battery composed of Zn/ZnSO4/Polyindole. This battery employs a neutral electrolytic solution. The reaction of the battery in the neutral electrolytic solution is accompanied with doping and de-doping of dopant anions. These dopant anions are large in size and low in mobility. Accordingly, this battery is disadvantageous to performances of fast charging and discharging.
An object of the present invention is to provide a secondary battery and capacitor having a high electromotive force together with a high cyclic property land being capable of fast charging and discharging, using a polymeric compound having a high stability and high reactivity in an acidic ambient, as an electrode active material.
In accordance with the present invention, a secondary battery and capacitor are provided, which include an indole polymeric compound as an electrode active material. The polymeric compound employs a proton as a charge carrier and has a constituent represented by general formula (1): 
In the general formula, each R denotes a hydrogen atom, a halogen atom, a hydroxyl group, a carboxyl group, a sulfonic group, a sulfuric acid group, a nitro group, a cyano group, an alkyl group, an aryl group, an alkoxyl group, an amino group, an alkylthio group and an arylthio group. R""s may be the same or different from each other. At least one R has a substituent other than a hydrogen atom. At least two R""s, are employed for bonding to form a polymer. These bonds may be double bonds.
Other features and advantages of the invention will be apparent from the following description of the preferred embodiments thereof.